Somatostatin (SST) is produced endogenously as two bioactive peptides which act on numerous target cells notably in the brain, pancreas, gastoinestinal tract, pituitary, adrenals and thyroid to regulate cell processes such sa neurotransmission, glandular secretion, smooth muscle contractility and cell proliferation (Reichlin, S., N. Eng. J. Med., 309:1495-1501 and 1556-1563 (1983)). Thus somatostatin can function as a neurotransmitter as well as a hormone. Its hormonal effects include suppression of release of many pituitary, pancreatic and gastrointestinal hormones, e.g., human growth hormone. The cellular actions of somatostatin are mediated by cell surface receptors (SSTRs), which transduce their intracellular signals via G protein-coupled pathways.
Somatostatin binds to a family of structurally-related proteins. Presently there are five known somatostatin receptor subtypes,designated SSTR1-5 (Yamada et al., Proc. Natl. Acad. Sci., 89:251-255 (1992), Yamada et al., Biochem. Biophys. Res. Comm., 195:844-852 (1993) and Patel et al., Biochem. Biophys. Res. Comm., 198:605-612 (1994)).
This invention thus provides a novel receptor of the human somatostatin subtype. The DNAs of this invention, such as the specific sequences disclosed herein, are useful in that they encode the genetic information required for expression of this novel class of somatostatin receptors. Additionally, the sequences may be used as probes in order to isolated and identify addition members of the family, type and/or subtype as well as forming the basis of antisense therapy for disease conditions which are characterized by atypical expression of the somatostatin gene. The novel protein is itself useful as a therapeutic, a diagnostic agent (e.g., antibodies that specifically bind to such protein), and as a component in a screening system for drugs which are antagonists or agonists of such receptor activity. These and additional uses for the reagents described herein will be come apparent to those of ordinary skill in the art upon reading this specification.